Diecasting method and device

ABSTRACT

A diecasting process and a diecasting device to shorten the cycle times. The closing of the mold and the filling of molten metal into a casting chamber ( 4 ) are performed simultaneously.

The invention relates to a diecasting method, in particular a method for diecasting parts out of metal alloys, in particular out of aluminum materials, magnesium or zinc materials, as well as to a device for diecasting such parts.

The manufacture of diecasting parts out of light metal melts is known in the art. To this end, a portion of the melt is filled into a casting chamber and pressed into a mold cavity with a plunger. During a shot, the transition between casting chamber and mold runner must be carefully sealed. Different types of sliders or valves, or check valves, can be used for this purpose.

Known from DE-C-10064300 is to design a mold runner in such a way that it exhibits a plug retaining space for a die-molded material plug to be removed, wherein the runner has at least two separate air channels, sections of each are designed as the plug retaining space.

DE-A-4326325 discloses a method for optionally evacuating a metallurgical vessel. The floor of the vessel has an evacuation port, in which some of the vessel content is made to solidify, thereby yielding a plug. The evacuation port sealed in this way can be opened by melting the plug. To this end, an induction heater is allocated to the evacuation port.

EP-B-1165274 discloses a diecasting mold, in particular for vacuum diecasting, with a device for evacuating the mold cavity and casting chamber, wherein a front opening in the casting chamber to the mold can be sealed by a die, wherein the die exhibits a flow restrictor channel. As a result, the casting chamber can be vented as the metal melt is already being moved toward this opening.

Known from EP-A-1407841 is a diecasting machine with a casting chamber that accommodates two reciprocally moving plungers to compress melts or subject them to further treatment in a specific area of the casting chamber.

The object of the invention is to develop a diecasting method that makes it possible to reduce the cycle time per shot for diecasting parts made out of aluminum, magnesium or zinc materials, or higher-melting metals like copper or steel. The object is achieved with the features specified in claims 1 or 2.

Making the mold closing and casting chamber filling (metering or filling during idle time) processes parallel makes it possible to save time and improve quality. The casting chamber is partially to completely filled with melt without interrupting the work cycle of the casting machine. The casting chamber is preferably part of a horizontal cold-chamber diecasting machine.

With the casting chamber filed and mold vented, the casting chamber contains no more air. The casting chamber can be 100% filled.

Advantageous embodiments are disclosed in the subclaims.

In a preferred embodiment, the seal is formed by mechanically moved sealing elements, in particular elements that act independently of each other.

In other embodiments, a material seal forms an opening in the casting chamber to the mold or runner. This material seal is preferably a plug, which can be disk-shaped, and is made at least out of partially-solidified material, wherein the material is cooled to below the liquidus temperature. Prior to the next shot, this plug must be at least partially melted, to which end use is made of the energy of the melt subsequently filled into the casting chamber and/or a heater.

The plunger must remain in front of the plug to be formed during the current shot.

In this case, no additional mechanically moved sealing elements are required, and no material is lost.

The process entails the following steps:

-   -   Closing the mold (including hinge tensioning, if necessary) and         filling the casting chamber     -   Initiating shot     -   Solidifying     -   Opening the mold     -   Partial removal     -   Spraying

Another object is to provide a diecasting device that enables a clear reduction in the cycle time for a shot. This object is achieved with the features described in claim 11. The device is characterized in that the opening in a casting chamber of a diecasting machine to a mold can be sealed by means of a moving seal.

Advantageous embodiments are disclosed in the accompanying subclaims.

In particular, this can be achieved with a plunger or slider that can shift horizontally or vertically.

However, the sealing element could also be a “plug” consisting of melt to be cast, as already mentioned.

The seal could also take the form of a magnetic field. The sealing element is preferably located on the fixed mold half, and at least partially closes the casting chamber or opening expanse. As a result, the sealing element can remain in this position during the shot, thereby also saving on time.

In addition, a flow front sensor according to DE-A-10011529 can be situated in the casting chamber to determine the fill level. In like manner, the machine controller could be used to backtrack and compute an optimal starting point for a shot, to include scanning a mold closing signal.

The sealing element can be coated in a suitable manner, and incorporate a heater or cooler.

In prior art, mold closure is followed by a determination of metering readiness, and by metering (filling) itself as an additional step.

In terms of the invention, idle time (FIG. 3) is the time taken up by an activity precluded from the cycle and executed parallel to other activities without altering the process.

The invention will be described in greater detail below in an exemplary embodiment based on a drawing. The drawing shows:

FIG. 1: The filling of the casting chamber and simultaneous mold closure

FIG. 2: Casting with closed slider

FIG. 3: Process flow chart

A diecasting machine exhibits a casting chamber 4 with a fill opening 6 for metal melt and a plunger 5. The casting chamber 4 is connected with a fixed mold half 1, which in turn corresponds with a moving mold half 2. Sliding the moving mold half 2 in the direction of arrow 7 creates the cavity 3. A vertically moving slider 8 is situated in front of an opening 9 of the casting chamber 4 to the mold. The opening 9 is part of the runner, and the upper part of the slider 8 can be designed in such a way that it helps form the beginning of the runner. The slider 8 can also completely seal the opening 9.

If the casting chamber 4 is now filled with a light metal melt 10, the moving mold half simultaneously shifts in the direction of the arrow 7, and the mold closes. Shortly before the filling process starts or at the latest in conjunction with the filling process, the slider 8 is moved up to at least partially seal the opening 9.

Once the mold is closed and the melt portion has been completely transferred into the casting chamber 4, the plunger 5 is traversed toward the opening 9, and the metal melt 10 is pressed into the cavity 3.

Metering into the casting chamber 4 can take place from above or below. An opening for metering from above can also be used as a matching hole for venting the casting chamber 4 (abatement of counter-pressure waves). In like manner, the mold can be vented while advancing the plunger 5.

A frontal opening to a runner in the cavity 3 of a mold lying opposite the plunger 5 can be completely sealed.

The opening is sealed in this way using a plug made out of the material to be cast. This plug is formed by “excess” metal melt by inserting the plunger 5 toward the opening after the casting chamber has been filled until the mold cavity is completely filled with metal melt, and a residual melt remains in the casting chamber 4 in front of the opening. This residual melt solidifies at least partially, thereby forming a plug. After the plunger 5 has been withdrawn and the casting chamber 4 has been filled for the next shot, the plug is at least partially melted again while advancing the plunger 5 by means of a heater. The heat of the metal melt can also be used, where possible.

After the shot, the mold is opened, and the slider 8 moves downward simultaneously (with the mold). The plunger 5 pushes out the residual pressed material, and the mold is sprayed for the next shot.

The slider 8 can consist of various materials suitable in terms of insulation, cooling or melting resistance.

Depending on need, the slider 8 can also completely close the opening 9 while introducing the metal melt 10, and the opening 9 is only completely or partially opened for pressing in the metal melt 10 (depending on the fill level of the casting chamber 4).

Similarly, the slider 8 could also be horizontally movable. In like manner, the slider 8 could be designed like a die.

In all instances, the slider 8 can be shifted parallel to the opening 9 of the casting chamber 4, wherein the slider 8 can then be arranged on guiding levers that can move at an angle.

In addition, the slider can exhibit an opening for allowing the melt through. The slider can also exhibit another vent hole. As a result, the casting chamber 4 can be vented while advancing the plunger 5 with the slider closed, after which the slider is as far as necessary for the melt to traverse the through hole in the slider and get into the mold cavity.

The fixed mold half 1 can also contain ejectors or the like.

The closed casting chamber 4 can be filled with the required melt quantity during a spraying process already. To minimize air pockets as much as possible, a relaxation time can be allowed to pass after the casting chamber 4 has been filled.

During the idle time, the plunger 5 advances to a point where the casting chamber 4 is nearly 100% full. Sealing the casting chamber 4 makes it possible to perform the mentioned processes with the mold open while spraying during the idle time. The cycle time is clearly reduced.

When opening the mold, the slider 8 can be kept closed to separate the cast part and tablet. As a result, the solidification time for the tablet can also be encompassed in the idle time.

If the casting chamber 4 is also thermally insulated, its heat loss can also be reduced. As an alternative, the casting chamber could also be cooled.

Pre-solidifying processes can be reduced, and the casting quality can be increased.

The casting chamber 4 can consist of a steel, be coated with a ceramic material, be clad with a ceramic sleeve or consist entirely of ceramic or a metal-matrix composite or a fully nitrated material fabricated via powder metallurgy.

REFERENCE LIST

-   1 Fixed mold half -   2 Moving mold half -   3 Cavity -   4 Casting chamber -   Plunger -   6 Fill opening -   7 Arrow -   8 Slider -   9 Opening -   10 Metal melt 

1. A diecasting method for a horizontal cold-chamber diecasting machine, comprising: filling a metal melt is into a casting chamber, after which the metal melt is pressed into a closed mold cavity via a plunger, and the cast part is removed after the melt has solidified, wherein the metal melt is filled into a casting chamber during idle time, and hence while closing the mold containing the mold cavity.
 2. A diecasting method for a horizontal cold-chamber diecasting machine, comprising: filling or metering a metal melt into a casting chamber, after which the metal melt is pressed into a closed mold cavity, wherein the mold is closed and casting chamber is filled simultaneously, and hence wherein the casting chamber is filled with metal melt with the mold open or while closing the mold.
 3. The diecasting method according to claim 1, wherein at least one opening from the casting chamber to the mold cavity is at least partially closed at the latest when the metal melt starts to be filled into the casting chamber.
 4. The diecasting method according to claim 3, wherein closure takes place magnetically, thermally or mechanically.
 5. The diecasting method according to claim 2, wherein the casting chamber is vented by moving the plunger.
 6. The diecasting method according to claim 1, wherein the tablet solidification period coincides with the idle time.
 7. The diecasting method according to claim 1, wherein a at least one opening to a casting channel of the cavity is tightly sealed after each shot.
 8. The diecasting method according to claim 7, wherein residual melt remains between the plunger and opening, which at least partially solidifies during or after a shot, closing the opening as a plug.
 9. The diecasting method according to claim 8, wherein the plunger traverses close to the opening at the time of plug formation.
 10. The diecasting method according to claim 7, wherein the plug is at least partially melted after the casting chamber is filled again.
 11. A diecasting method for implementing a method according to claim 1, wherein the horizontal cold chamber diecasting machine, comprises a casting chamber with fill hole for filling in the metal melt and a plunger arranged in the casting chamber, and the casting chamber is joined with a fixed mold half, which corresponds with a moving mold half, and an opening in the casting chamber empties into a runner of a mold cavity, wherein a sealing element is movably arranged in front of the opening to at least partially seal the opening.
 12. The device according to claim 11, wherein the sealing element is a horizontally and/or vertically moving slider.
 13. The device according to claim 11, wherein the sealing element and/or the opening are part of the runner.
 14. The device according to claim 11, wherein the casting chamber and/or the slider comprise metal and/or ceramic or composite materials.
 15. The device according to claim 14, wherein the casting chamber and/or the sealing element comprise a nitrated material fabricated via powder metallurgy.
 16. The device according to claim 12, wherein the slider shifts parallel to the opening of the casting chamber.
 17. The device according to claim 12, wherein the slider is provided with a PVD coating.
 18. The device according to claim 12 wherein a heater or cooler is integrated into the slider. 